Last Friday, right at the point in the weekly news cycle when things are announced by people who don’t want them noticed, comedian and actor Patton Oswalt did the opposite: he wrote something that was instantly noticed, at least within the comedy-adjacent world, and that continued to be the subject of discussion for days after. On his blog, Oswalt published a “closed letter” to himself, an eloquent 6,000-word meditation on a few hot-topic subjects: joke theft, heckling and rape jokes.

“I wrote it to sort out stuff in my own head,” Oswalt tells TIME. “I didn’t know it would catch on like that. It’s very flattering.”

In the days that followed, the segment on rape jokes garnered the most attention. Oswalt reversed a previous defense of those who cry “censorship!” at any discussion of whether and how a topic should be addressed. It’s a fascinating look at his thought process and a worthwhile contribution to a much larger conversation. (Jezebel is a good place to start if you haven’t been following that discussion, not because only feminist blogs can talk about rape culture but because they’ve been on top of the topic from the beginning.) However, it’s the section about people who steal jokes that’s probably the most revelatory to those outside the comedy community.

Here’s the deal: Over the last few years, several individuals—from a Twitter-famous pastor to a Columbia student speaking at commencement—have attempted to pass off Oswalt’smaterial as their own. Oswalt admits that sometimes someone else’s joke sneaks into one’s brain without attribution, leading to an accidental instance of punch-line thievery. But the correct thing to do in that case is apologize and not do it again. What he takes issue with is people who believe that joke-theft is not a big deal, that everyone does it and nobody cares, that jokes don’t belong to anyone so they can’t actually be stolen, that it only matters how well you tell them. Which, he says, is the opposite of the truth.

One of the more surprising roots of joke theft is the belief that comedians don’t write their own material anyway. “I encounter that idea from really, really dumb people or, oddly enough, really, really intelligent people,” Oswalt says, noting that he thinks very smart people who lack the comedy gene must think it’s impossible for drop-outs who work at nightclubs to be able to do something they can’t, which is “a sad way to live your life.”

That’s not the only reason a person without a sense of humor might get the idea that all jokes are up for grabs. “When they argue that all jokes sound the same, they’re not lying. They really can’t hear the difference between a really amazing, personal joke, like Bill Cosby‘s massive ‘Revenge,’ and a knock-knock-who’s-there joke,” he says. That’s like not being able to tell the difference between a bedtime fable and a novel. Oswalt isn’t advocating that amateurs stop telling classic jokes and riddles to their friends at home (something that pro-joke-theft writers sometimes bemoan) but that people who are speaking—or tweeting—publicly stop trying to pretend they came up with things they didn’t when the material has an identifiable author, and then rationalizing their actions with theories about the nature of comedy.

He says that part of the impetus for his writing about the topic was the feeling that the mainstream, the non-dumb/non-“sequestered smarty”/non-humorless masses, were starting to lose that distinction too. One of the common arguments helping that thought process creep forward is that, back in the days of Vaudeville—the Paleolithic era of stand-up – joke theft was normal, and, therefore, modern comics should get over it.

“That’s so friggin’ wrong,” says Oswalt. “Vaudeville, as far as comedy’s concerned, was like gangsta hip-hop. W.C. Fields would wait outside the stage doors for guys who would do his act and beat the living s**t out of them.”

Herewith, a brief history of joke theft:

Vaudeville:

Yes, joke theft happened in vaudeville. When all comedy was live and on the road, it was relatively easy to take some else’s act to the next town before he got there himself, explains TIME’s resident comedy expert, Richard Zoglin. But that doesn’t mean everyone was okay with it. Trade associations for vaudeville artists, along with other organizations, offered registry services: file your jokes with officials and, if there’s a question over who thought of it first, you’ll be able to get an answer. (The trade group could also impose penalties on the thief.) For those interested, Emerson College has an archive of acts registered with the New York Clipper, a defunct trade paper.

Milton Berle is perhaps the most famous joke thief ever, and didn’t exactly deny it. The thievery caused Hollywood feuds—Zoglin says that, according to showbiz legend, Bob Hope was once so mad at Milton Berle that at a series of benefits in New York in the 1930s he went on stage first and did all of Berle’s material. In later interviews, Berle claimed that it was all a publicity hoax, that he wasn’t really a thief:

Robin Williams:

Though Williams is seriously funny and seriously famous in his own right, he also had a serious reputation for stealing material in the 1980s. According to a joke-theft story published by Radar in 2007, Williams would pull out his wallet and pay those who came up with the jokes—if confronted about it.

Mencia is another fairly well known comedian with an unsavory reputation. In 2006, George Lopez publicly called him out for stealing nearly a quarter-hour of material, and Lopez isn’t the only one who sees Mencia’s material as a little too familiar. Confronted about the accusations in a 2010 interview, Mencia says it’s all just coincidence.

Dane Cook:

The question of whether Dane Cook lifted material from Louis C.K. in 2006 is perhaps the biggest recent dust-up in the annals of joke theft. It came to an interesting conclusion in 2011 when Cook appeared on Louie to have a scripted, fictional conversation with Louis C.K. In exchange for Lady Gaga tickets for Louie’s daughter, Cook wants Louie to publicly say that the theft didn’t happen. The scene doesn’t exactly settle the matter once and for all, but it sure makes it clear that two of the biggest comedians out there do really, really care about joke-theft—which was a big part of the point Oswalt wanted to make.

So what comes next?

“I know I’m never going to win this fight,” says Oswalt. “I’m happy to keep fighting it because it’s a very simple fight to win—and also I want really creative, risk-taking people to be drawn to my profession. When someone comes along and steals from them, it makes the idealistic and the creative undeservedly cynical. It’s the thieves who should feel uncomfortable, because of their lack of talent.”